The "Query Compiler, Rewrite, Optimizer" component in IBM DB2 UDB 9.5 before FP6a allows remote authenticated users to cause a denial of service (CPU consumption) via a crafted query involving certain UNION ALL views, leading to an indefinitely large amount of compilation time.
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A14736